In recent years, among mobile terminals such as cellular phones, electronic devices are increasingly provided with a contact detection unit, such as a touch sensor or touch switch, as a member for detecting an operation by the operator. Electronic devices provided with a contact detection unit are in wide use apart from mobile terminals as well, in devices such as calculators or ticket vending machines, household appliances such as microwave ovens, televisions, or lighting appliances, industrial devices (factory automation equipment), and the like.
A variety of types of such contact detection units are known, including a resistive film type and a capacitive type. All of these types of contact detection units detect contact by the operator's finger, a stylus pen, or the like. Typically, an electronic device provided with a contact detection unit displays an image (hereinafter referred to as an “object”) of an operation key, a button, or the like (hereinafter referred to simply as “operation key or the like”) on the display screen of a display unit provided on the rear face of the contact detection unit. When the operator presses an object displayed on the display screen, the contact detection unit is configured to detect contact at the position of the press.
By controlling the size of the input display image based on the contact area of the operator's finger with the contact detection unit and on the pressure load, known electronic devices prevent a determination that two or more input areas are being pressed simultaneously even when the operator has a large fingertip (large contact area) and avoid input error even when an inexperienced operator performs input operations (for example, Patent Literature 1). Other electronic devices resolve erroneous input operations, such as misalignment or multiple input that are characteristic for each operator, by adjusting the allowable input area individually for each operator (for example, see Patent Literature 1 and 2).
Furthermore, to prevent processing by the electronic device from being performed when the contact detection unit is simply brushed lightly with a finger, while also providing an operator with a real tactile sensation, as when pressing an actual button, upon the operator pressing an object, an electronic device has been proposed to receive input when a pressure load satisfying a predetermined input receiving standard is applied to the contact detection unit and to provide a predetermined tactile sensation to the operator's fingertip, for example by vibrating the contact detection unit. Hereinafter, such an electronic device is referred to as an “electronic device having a tactile sensation providing function”.